(1) Confirmation that near-ultraviolet irradiation (NUV) in the presence of hydrogen peroxide (H202) produces crosslinks of protein with DNA in biological systems. (2) Identification of specific amino acid(s) and base(s) that crosslink. (3) Repair experiments: Nuv irradiation produces DNA-protein crosslinking in mouse cell lines (L929 fibroblasts and B-16 melanoma). These crosslinks are repaired within 24 hr after NUV treatment. When L929 fibroblasts are exposed to Trans-Pt (II) Diamine dichloride (Trans-Pt), comparable DNA-protein crosslinking occurs. We plan to complete the studies currently underway on repair of Trans-Pt induced DNA-protein crosslinking; analysis of proteins induced during the repair periods in an attempt to identify potential repair-related proteins; and extrapolate the NUV and Trans-Pt treatment studies to human cell lines, including repair-deficient mutant lines Xeroderma pigmentosum, Cockayne's Syndrome (both of which show increased UV sensitivity), and Ataxia telangiectasia, Bloom's Syndrome and Fanconi's Anemia (all of which show increased chromosome breakage). (4) We will examine the enzymes that are induced by various damages to DNA, including mutagens and carcinogens. A comparison will be made of mechanisms of NUV damage and repair. Enzymes will be induced, separated by acrylamide gels, and compared with each other.